U.S. patent application number 10/786202 was filed with the patent office on 2004-08-26 for crane radial support bearing.
Invention is credited to Delago, Pierre C..
Application Number | 20040164040 10/786202 |
Document ID | / |
Family ID | 32927610 |
Filed Date | 2004-08-26 |
United States Patent
Application |
20040164040 |
Kind Code |
A1 |
Delago, Pierre C. |
August 26, 2004 |
Crane radial support bearing
Abstract
The present invention, in one embodiment, is a system for
receiving and delivering into a base the radial loads imposed on a
crane where the crane has a center post operably connected to the
base with a generally cylindrical outer bearing surface and the
crane rotates in at least a partial circle around the axis of the
center post. The system comprises three or more radial load rollers
arranged in a linked sequence in an arc at the outer bearing
surface of the center post. Each radial load roller includes an
axle and an axis of rotation that is generally parallel to the axis
of the center post. The system also comprises a means for anchoring
a first radial load roller at one end of the arc and anchoring a
second radial load roller at the other end of the arc. The system
also comprises links connecting each roller between the first and
the second radial rollers to its adjacent rollers to form a
flexible chain of said rollers. Finally, the system comprises a
means for tensioning the linked radial load rollers to draw each
radial load roller into rolling contact with the outer bearing
surface and to equalize substantially the radial forces exerted by
the radial rollers on the outer bearing surface.
Inventors: |
Delago, Pierre C.; (Afton,
MN) |
Correspondence
Address: |
Stuart R. Hemphill, Esq.
DORSEY & WHITNEY LLP
Intellectual Property Department
50 South Sixth Street, Suite 1500
Minneapolis
MN
55402-1498
US
|
Family ID: |
32927610 |
Appl. No.: |
10/786202 |
Filed: |
February 25, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60450081 |
Feb 25, 2003 |
|
|
|
Current U.S.
Class: |
212/253 |
Current CPC
Class: |
B66C 23/84 20130101;
F16C 2300/14 20130101; F16C 19/50 20130101; F16C 2326/00
20130101 |
Class at
Publication: |
212/253 |
International
Class: |
B66C 023/84 |
Claims
We claim:
1. A system for receiving and delivering into a base the radial
loads imposed on a crane, wherein the crane has a center post
operably connected to the base, the center post has a generally
cylindrical outer bearing surface, and the crane rotates in at
least a partial circle around a rotational axis of the center post,
the system comprising: a plurality of rollers arranged in a linked
sequence along the outer bearing surface of the center post, each
roller having an axis of rotation that is generally parallel to the
rotational axis of the center post; an anchor for anchoring a first
roller at one end of the linked sequence and an anchor anchoring a
second roller at the other end of the linked sequence; and a link
connecting each roller between the first and the second rollers to
its adjacent rollers to form a flexible chain of said rollers,
wherein the linked rollers are in rolling contact with the outer
bearing surface.
2. The system of claim 1, wherein the link comprises pivoting links
and fixed links, wherein each roller between the first and second
rollers is connected by a pivoting link to one of its adjacent
rollers and by a fixed link to the other of its adjacent
rollers.
3. The system of claim 1, further comprising a back roller
including a rotational axis generally parallel to the rotational
axis of the center post and a roller surface in rolling contact
with the outer bearing surface, wherein the back roller is secured
to a superstructure of the crane and positioned along the outer
bearing surface in a location not encompassed by the flexible chain
of rollers.
4. The system of claim 1, further comprising a containing pad
secured to the crane center post and/or a superstructure of the
crane and adapted to prevent the displacement of the flexible chain
of rollers in at least one vertical direction.
5. The system of claim 1, further comprising a flange supported off
of a superstructure of the crane and adapted to prevent the
displacement of the flexible chain of rollers in at least one
vertical direction.
6. The system of claim 1, wherein the flexible chain of rollers
encompasses at least approximately 120 degrees of the cylindrical
outer bearing surface of the crane center post.
7. The system of claim 1, wherein the flexible chain of rollers
encompasses at least approximately 180 degrees of the cylindrical
outer bearing surface of the crane center post.
8. The system of claim 1, wherein the flexible chain of rollers
encompasses at least approximately 270 degrees of the cylindrical
outer bearing surface of the crane center post.
9. The system of claim 1, wherein the outer bearing surface
comprises a rail and the rollers are flanged to engage the
rail.
10. The system of claim 1, wherein the rollers have a double
inclined face, the outer bearing surface comprises a rail with a V
profile, and the double inclined face of the rollers matingly
interfaces with the V profile of the rail.
11. The system of claim 1, wherein each roller has a face, at least
a portion of which is arcuate, the outer bearing surface comprises
a profile, at least a portion of which is arcuate, and the arcuate
portion of the roller faces matingly interface with the arcuate
profile of the rail.
12. A method for receiving and delivering into a base the radial
loads imposed on a crane, wherein the crane has a center post
operably connected to the base, the center post has a generally
cylindrical outer bearing surface, and the crane rotates in at
least a partial circle around a rotational axis of the center post,
the method comprising: providing a plurality of rollers in a linked
sequence along the outer bearing surface of the center post, each
roller having an axis of rotation that is generally parallel to the
rotational axis of the center post; providing anchors for anchoring
a first roller at one end of the linked sequence and anchoring a
second roller at the other end of the linked sequence; providing
each roller between the first and the second rollers with a link to
its adjacent rollers to form a flexible chain of said rollers; and
tensioning the linked sequence to draw each roller into rolling
contact with the outer bearing surface.
13. The method of claim 12 wherein the link to the adjacent rollers
comprises pivoting links and fixed links, wherein each roller
between the first and second rollers is connected by a pivoting
link to one of its adjacent rollers and by a fixed link to the
other of its adjacent rollers.
14. The method of claim 12, further comprising providing a back
roller including a rotational axis generally parallel to the
rotational axis of the center post and a roller surface in rolling
contact with the outer bearing surface, wherein the back roller is
secured to a superstructure of the crane and positioned along the
outer bearing surface in a location not encompassed by the flexible
chain of rollers.
15. The method of claim 12, further comprising preventing the
displacement of the flexible chain of rollers in at least one
vertical direction.
16. The method of claim 12, further comprising encompassing at
least approximately 120 degrees of the cylindrical outer bearing
surface of the crane center post with the flexible chain of
rollers.
17. The method of claim 12, further comprising encompassing at
least approximately 180 degrees of the cylindrical outer bearing
surface of the crane center post with the flexible chain of
rollers.
18. The method of claim 12, further comprising encompassing at
least approximately 270 degrees of the cylindrical outer bearing
surface of the crane center post with the flexible chain of
rollers.
19. A bearing system comprising: a bearing surface forming at least
a partial arc about a first axis; and a roller chain encompassing
at least a segment of the bearing surface and comprising: a first
roller, a second roller, and a third roller, each roller including
a rotational axis generally parallel to the first axis and a roller
surface in rolling contact with the bearing surface, wherein the
rollers are radially offset from each other along the bearing
surface; a first member interlinking the first and second rollers
and maintaining an offset distance between the first and second
rollers; and a second member interlinking the second and third
rollers and maintaining an offset distance between the second and
third rollers.
20. The bearing system of claim 19, wherein the arc about the first
axis is a generally cylindrical outer surface of a crane center
post.
21. The bearing system of claim 20, wherein the roller chain
further includes a first end and a second end, said ends being
operably coupled to a crane superstructure that supports a
boom.
22. The bearing system of claim 21, further comprising a back
roller including a rotational axis generally parallel to the first
axis and a roller surface in rolling contact with the bearing
surface, wherein the back roller is operably coupled to the crane
superstructure and positioned along the bearing surface in a
location not encompassed by the roller chain.
23. The bearing system of claim 21, wherein the crane
superstructure includes a first anchor adapted to operably couple
the first end of the roller chain to the crane superstructure and a
second anchor adapted to operably couple the second end of the
roller chain to the crane superstructure.
24. The bearing system of claim 23, wherein the first and second
members are link plates and the first and second anchors each
operably couple to the roller chain with an extended link
plate.
25. The bearing system of claim 21, wherein the crane
superstructure includes means for anchoring the first end and the
second end of the roller chain to the crane superstructure.
26. The bearing system of claim 21, further comprising a
containment pad secured to the crane center post and/or the crane
superstructure and adapted to prevent the displacement of the
roller chain in at least one vertical direction.
27. The bearing system of claim 21, further comprising a flange
supported by the crane superstructure and adapted to prevent the
displacement of the roller chain in at least one vertical
direction.
28. The bearing system of claim 20, wherein the roller chain
encompasses at least approximately 120 degrees of the cylindrical
outer surface of the crane center post.
29. The bearing system of claim 20, wherein the roller chain
encompasses at least approximately 180 degrees of the cylindrical
outer surface of the crane center post.
30. The bearing system of claim 20, wherein the roller chain
encompasses at least approximately 270 degrees of the cylindrical
outer surface of the crane center post.
31. The bearing system of claim 19, wherein the radial offset
between the first and second rollers is between approximately two
degrees and approximately 20 degrees.
32. The bearing system of claim 19, wherein the radial offset
between the first and second rollers is between approximately five
degrees and approximately 15 degrees.
33. The bearing system of claim 19, wherein the radial offset
between the first and second rollers is approximately 10
degrees.
34. The bearing system of claim 19, wherein the first member is
non-pivoting relative to the rotational axes of the first and
second rollers, and the second member is pivotal relative to the
rotational axes of the second and third rollers.
35. The bearing system of claim 19, wherein the first member is
pivotal relative to the rotational axes of the first and second
rollers, and the second member is pivotal relative to the
rotational axes of the second and third rollers.
36. The bearing system of claim 19, wherein the outer bearing
surface is a rail and at least one roller is flanged to engage the
rail.
37. The bearing system of claim 19, wherein at least one roller has
a double inclined face, the outer bearing surface is a rail with a
V profile, and the double inclined face of the at least one roller
matingly interfaces with the V profile of the rail.
38. The bearing system of claim 19, wherein each roller has a face,
at least a portion of which is arcuate, the outer bearing surface
comprises a rail with a profile, at least a portion of which is
arcuate, and the arcuate portion of the roller faces matingly
interface with the arcuate profile of the rail.
39. The bearing system of claim 19, further comprising means for
preventing the displacement of the roller chain in at least one
vertical direction.
40. The bearing system of claim 19, further comprising a
containment pad adapted to prevent the displacement of the roller
chain in at least one vertical direction.
41. The bearing system of claim 19, further comprising a flange
adapted to prevent the displacement of the roller chain in at least
one vertical direction.
42. A method of delivering radial loads from a first structure into
a bearing surface of a second structure, wherein the bearing
surface forms at least a partial arc about a first axis and the
first structure is rotationally displaceable about the first axis,
the method comprising: routing a roller chain along at least a
portion of the bearing surface, said roller chain including a first
end, a second end, and a plurality of flexibly interlinked rollers
between the first and second ends, each roller including an axis of
rotation that is generally parallel to the first axis; operably
connecting the first end of the roller chain to a first anchor
point on the first structure; operably connecting the second end of
the roller chain to a second anchor point on the first structure;
and causing each roller to rollably contact the bearing
surface.
43. The method of claim 42, further comprising causing the roller
chain to radially displace along the bearing surface as the first
structure rotates about the first axis.
44. The method of claim 43, wherein the rollers rollably travel
along the bearing surface as the roller chain radially displaces
along the bearing surface.
45. The method of claim 42, wherein the first and second anchor
points are radially offset from each other about the first axis by
at least approximately 120 degrees.
46. The method of claim 42, wherein the first and second points are
radially offset from each other about the first axis by at least
approximately 180 degrees.
47. The method of claim 42, wherein the first and second points are
radially offset from each other about the first axis by at least
approximately 270 degrees.
48. The method of claim 42, further comprising tensioning the
roller chain to equalize substantially the radial loads applied by
the interlinked rollers to the bearing surface.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority from U.S. Provisional
Patent Application No. 60/450,081, filed on Feb. 25, 2003, which is
hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an apparatus and methods
for resisting thrust loads on a crane. More specifically, the
present invention relates to a bearing system for resisting radial
(i.e., horizontal) thrust loads from a boom on a post crane.
[0003] Ships and offshore platforms need cranes to rapidly and
safely load and off-load various material and personnel. Affixable,
pedestal-type cranes with a center post have been very popular in
marine type applications. On a post crane, the superstructure and
boom of the crane rotate on bearings about the axis of the
post.
[0004] The post serves as the crane's structural base for resisting
the thrust loads and overturning moments experienced by the crane.
The thrust loads are transferred from the boom to the post via the
bearings on which the superstructure rotates about the axis of the
post. Specifically, vertical thrust loads are transferred from the
boom to the post via a container ring bearing, which comprises a
plurality of rollers. Radial (i.e., horizontal) thrust loads are
transferred from the boom to the post via the radial bearing ring
comprising a plurality of rollers, which rollably engage the outer
circumference of the post.
[0005] While the post crane has many advantages over other types of
cranes in a marine environment, the ability to achieve equal
bearing loading about the bearings, especially the radial bearing
ring, has been challenging. Failure to achieve equal loading about
the bearings can result in uneven bearing roller wear, which can
lead to premature repairs and downtime for the crane or even
catastrophic failure of the crane.
[0006] To achieve equal roller loading about the radial bearing
ring, manufacturers have had to rely on precision machining of the
bearing ring and its rollers or structures that permit elastic
deflections. Both options are less than desirable due to their
expense. Also, the commercially available precision bearings with
integral rings are limited in size to 6.5 meters in diameter, which
in turn limits the load capacity of the crane. There is a need in
the art for a more cost effective means of achieving equal roller
loading about the radial bearing ring.
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention, in one embodiment, is a system for
receiving and delivering into a base the radial loads imposed on a
crane where the crane has a center post operably connected to the
base with a generally cylindrical outer bearing surface and the
crane rotates in at least a partial circle around the axis of the
center post. The system comprises three or more radial load rollers
arranged in a linked sequence in an arc at the outer bearing
surface of the center post. Each radial load roller includes an
axle and an axis of rotation that is generally parallel to the axis
of the center post. The system also comprises a means for anchoring
a first radial load roller at one end of the arc and anchoring a
second radial load roller at the other end of the arc. The system
also comprises links connecting each roller between the first and
the second radial rollers to its adjacent rollers to form a
flexible chain of said rollers. Finally, the system comprises a
means for tensioning the linked radial load rollers to draw each
radial load roller into rolling contact with the outer bearing
surface and to equalize substantially the radial forces exerted by
the radial rollers on the outer bearing surface.
[0008] In another embodiment of the aforementioned system, the
links connecting each roller between the first and second rollers
comprise pivoting links and fixed links. Each roller between the
first and second rollers is connected by pivoting links to one of
its adjacent rollers and by fixed links to the other of its
adjacent rollers.
[0009] The present invention, in another embodiment, is a method
for receiving and delivering into a base the radial loads imposed
on a crane where the crane has a center post connectable to a base
with a generally cylindrical outer bearing surface and the crane
rotates in at least a partial circle around the axis of the center
post. The method comprises providing a linked sequence of three or
more radial load rollers arranged in an arc at the outer bearing
surface of the center post. Each radial roller has an axle and an
axis of rotation that is generally parallel to the axis of the
center post. The method also comprises providing a means for
anchoring a first radial load roller at one end of the arc and
anchoring a second radial load roller at the other end of the arc.
The method also comprises connecting each roller between the first
and the second radial rollers with links to its adjacent rollers to
form a flexible chain of said rollers. Finally, the method
comprises providing a means for tensioning the sequence of radial
load rollers to draw each radial load roller into rolling contact
with the outer bearing surface and causing the pivoting and fixed
links to equalize substantially the radial forces exerted by the
radial rollers on the outer bearing surface.
[0010] In another embodiment of the aforementioned method, the
links used to connect each roller between the first and second
rollers to its adjacent rollers are pivoting links and fixed links.
Each roller between the first and second rollers is connected by
pivoting links to one of its adjacent rollers and by fixed links to
the other of its adjacent rollers.
[0011] The present invention, in another embodiment, is a bearing
system including a bearing surface forming a circumference about a
first axis, and a roller chain encompassing at least a segment of
the bearing surface. The roller chain includes a first roller, a
second roller, a third roller, a first member, and a second member.
Each roller includes a rotational axis and a roller surface. The
rotational axis for each roller is generally parallel to the first
axis, and each roller surface is in rollable contact with the
bearing surface. The rollers are radially offset from each other
along the bearing surface. The first member interlinks the first
and second rollers and maintains the offset distance between the
first and second rollers. The second member interlinks the second
and third rollers and maintains the offset distance between the
second and third rollers.
[0012] In one embodiment, the first member is non-rotational
relative to the rotational axes of the first and second rollers,
and the second member is rotational relative to the rotational axes
of the second and third rollers. In another embodiment, the first
member is rotational relative to the rotational axes of the first
and second rollers, and the second member is rotational relative to
the rotational axes of the second and third rollers.
[0013] The present invention, in another embodiment, is a method of
delivering radial loads from a first structure into a bearing
surface of a second structure. The bearing surface forms a
circumference about a first axis and the first structure is
rotationally displaceable about the first axis. The method includes
routing a roller chain along at least a circumferential segment of
the bearing surface. The roller chain has a first end, a second
end, and a plurality of flexibly interlinked rollers between the
first and second ends. Each roller includes an axis of rotation
that is generally parallel to the first axis. The method further
includes operably connecting the first end of the roller chain to a
first point on the first structure, operably connecting the second
end of the roller chain to a second point on the first structure,
and causing each roller to rollably contact the bearing
surface.
[0014] In one embodiment, during operation, the roller chain
radially displaces along the bearing surface as the first structure
rotates about the first axis. As the roller chain displaces along
the bearing surface, the rollers rollably travel along the bearing
surface.
[0015] While multiple embodiments are disclosed, still other
embodiments of the present invention will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the invention. As
will be realized, the invention is capable of modifications in
various obvious aspects, all without departing from the spirit and
scope of the present invention. Accordingly, the drawings and
detailed description are to be regarded as illustrative in nature
and not restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a side elevation view of a post crane.
[0017] FIG. 2 is a detailed side elevation of the superstructure of
the crane shown in FIG. 1.
[0018] FIG. 3 is a detailed cross-sectional view of FIG. 2.
[0019] FIG. 4A is a detailed cross-section elevation of the chain
segment located within cloud A of FIG. 3.
[0020] FIG. 4B is a detailed cross-section elevation of an
alternate embodiment of the chain segment located within cloud A of
FIG. 3.
[0021] FIG. 5 is a cross-section plan view of half of the post and
machine deck taken across section line AA in FIG. 2.
[0022] FIG. 6 is a detailed cross-sectional view of FIG. 2 in
another embodiment of the invention.
[0023] FIG. 7 is a cross-section plan view of half of the post and
machine deck taken across section line AA in FIG. 2 in another
embodiment of the invention.
[0024] FIG. 8 is a lateral cross-section elevation view of the
roller chain bearing, wherein the view cuts across the pivot link
plates between two rollers.
DETAILED DESCRIPTION
[0025] FIG. 1 is a side elevation view of a post crane 1 having a
tapered post 5, a boom 10, a swivel post-head 15 swivelly mounted
on top of the tapered post 5, and a superstructure 20. The boom 10
is pivotally connected to the superstructure 20 at the boom foot 22
and supported by wire rope 25 running from the swivel post-head 15
to locations on the boom 10. The post 5 may be rigidly mounted to
any desired supporting structure or base (not shown) such as a
pedestal of an off-shore platform, a ship deck, a moveable
vehicular frame, a permanent foundation embedded in the earth, or
any other structure. The superstructure 20 and swivel post-head 15
may rotate about the vertical axis 30 of the tapered post 5,
thereby allowing the boom 10 to displace radially about the
vertical axis 30 of the post 5. The post 5 supports the
superstructure 20 and serves as the primary structure for resisting
the thrust loads, radial loads, and overturning moments experienced
by the crane 1.
[0026] FIG. 2 is a detailed side elevation of the superstructure 20
and more clearly shows the connection of the boom 10 to a boom
pivot point 32 on the boom foot 22. Below the superstructure 20, a
support collar 35 is connected to the post 5 and encompasses the
outer circumference of the post 5. The support collar 35 supports a
container ring 40, which encircles the outer circumference of the
post 5. An annular ring 45, which is part of the superstructure 20
and encircles the outer circumference of the post 5, rides on the
container ring 40. The annular ring 45 supports a machine deck 50
to which the boom foot 22 is mounted.
[0027] For a better understanding of the relationship between the
support collar 35, the container ring 40, the annular ring 45, and
the machine deck 50, reference is now made to FIG. 3, which is a
detailed cross-sectional view of FIG. 2. As shown in FIG. 3, the
annular ring 45 comprises the machine deck 50, an outer vertical
wall 55, a roller plate 60, and a first pair of rails 65. The
machine deck 50 encircles the post 5 and forms the top surface of
the annular ring 45. The outer vertical wall 55 runs from the
machine deck 50 and tees into the roller plate 60. The first pair
of rails 65 is connected to the bottom surface of the roller plate
60. The annular ring 45 and machine deck 50 are rotationally
displaceable about the outer circumference of the post 5.
[0028] As illustrated in FIG. 3, the support collar 35 encompasses,
and is connected to, the outer circumference of the post 5. The
support collar 35 comprises a flat upper deck 70 and a second pair
of rails 75. The second pair of rails 75 is mounted on the top of
the upper deck 70.
[0029] As indicated in FIG. 3, the container ring 40 comprises
pairs of flanged rollers 80 encircling the outer circumference of
the post 5. The flanged rollers 80 ride on the second pair of rails
75 and the first set of rails 65 ride on the flanged rollers 80.
Thus, the flanged rollers 80 of the container ring 40 support the
annular ring 45 above the support collar 35 and allow the annular
ring 45 to rotate about the axis 30 of the post 5. The support
collar 35 carries substantially all of the vertical (thrust) loads
of the crane 1 into the post 5.
[0030] In one embodiment of the invention, as shown in FIG. 3, a
stewing gear assembly 85, a first back roller 90, a second back
roller 95, and a roller chain bearing 100 are located on or above
the machine deck 50. In another embodiment of the invention, the
first back roller 90 is not present. FIG. 3 shows in phantom the
elevation location of the boom pivot point 32 relative to the
machine deck 50 and the post 5. The first and second back rollers
90, 95 and the roller chain bearing 100 are used to carry radial
(i.e., horizontal) loads, which are induced by the thrust of the
boom 10, into the post 5. The roller chain bearing 100 comprises
interlinking chain segments 102, which have horizontally oriented
rollers 105 connected together by pairs of pivot link plates 110
and fixed link plates 115. As indicated in phantom, the post 5 has
structural reinforcement 101 along the interior circumference of
the post 5. This structural reinforcement 101 allows the post 5 to
withstand the loads exerted on the post 5 by the rollers 105 of the
roller chain bearing 100.
[0031] For a better understanding of the structure of the roller
chain bearing 100, reference is now made to FIG. 4A, which is a
detailed cross-section elevation of the chain segment 102 located
within cloud A of FIG. 3. As shown in FIG. 4A, the chain segment
102 has two horizontally oriented rollers 105, a pair of fixed link
plates 115, two vertically oriented roller axles 120, two pairs of
annular bearings 125, two pairs of annular bearing covers 130, two
pairs of annular bushings 132, four sets of bolts 135, and four
axle covers 140. Each chain segment 102 is connected to the pairs
of pivot link plates 110 of the adjacent chain segments 102. Thus,
the chain segments 102 anchored to the machine deck 50 at each end
of the roller chain bearing 100 will have one adjacent chain
segment 102 and, as a result, will be connected to only one pair of
pivot link plates 110. All other chain segments 102 of the roller
chain bearing 100 will have two adjacent chain segments 102 and, as
a result, will be connected to two pairs of pivot link plates
110.
[0032] As illustrated in FIG. 4A, each roller 105 is rollably
supported about a roller axle 120 by a pair of bearings 125. A
bearing cover 130 encircles each roller axle 120 and is located
adjacent to the outside surface of each bearing 125. The end of
each roller axle 120 resides in an opening 145 in a fixed link
plate 115 near the end of the fixed link plate 115. The bolts 135
secure a fixed link plate 115 and an axle cover 140 to each end of
a roller axle 120. This prevents a roller axle 120 from
rotationally displacing within the opening 145 of a fixed link
plate 115.
[0033] Each roller axle 120 resides within two bushings 132, which
are located in openings 150 in the pivot link plates 110 near the
ends of the pivot link plates 110. Thus, each pair of pivot link
plates 110 may pivot about a roller axle 120 via a pair of bushings
132.
[0034] In another embodiment, as indicated in FIG. 4B, a set of
outer pivot link plates 116 (i.e., a second set of pivot link
plates) is substituted for the fixed link plates 115. The end of
each roller axle 120 resides within a bushing 132, which is located
in an opening 145 in the outer pivot link plate 116 near the end of
a outer pivot link plate 116. The bolts 135 secure an axle cover
140 to each end of a roller axle 120. Again, each roller axle 120
resides within two bushings 132, which are each located in an
opening 150 of the pivot link plate 110 near the end of a pivot
link plate 110. Thus, in the embodiment depicted in FIG. 4B, each
pair of pivot link plates 110 and outer pivot link plates 116 may
pivot about a roller axle 120 via a pair of bushings 132.
[0035] For an understanding of the arrangement of the roller chain
bearing 100 and its interaction with the post 5, reference is now
made to FIG. 5, which is a cross-section plan view of half of the
post 5 and machine deck 50 taken across section line AA in FIG. 2.
FIG. 5 shows half of a roller chain bearing 100 that, in one
embodiment, forms a 180-degree arc about the outer surface of the
post 5. FIG. 5 also shows a boom foot 22 located at approximately
the two o'clock position. This boom foot 22 is one of the two boom
feet 22 mounted on the machine deck 50. FIG. 5 also shows back
rollers 90, 95 located at the four-thirty and six o'clock positions
and structural reinforcement 101 on the interior circumference of
the post 5. The back rollers 90, 95 are two of the three back
rollers 90, 95 mounted on the machine deck. In other embodiments of
the invention, there may be a greater or lesser number of back
rollers 90, 95. For example, in one embodiment, the first back
roller 90 (i.e., the back roller at the six o'clock position) is
not present. The structural reinforcement 101 allows the post 5 to
withstand the loads exerted on the post 5 by the rollers 105 of the
roller chain bearing 100 and the back rollers 90, 95.
[0036] It should be noted that the arrangements of the roller chain
bearing 100, the back rollers 95, and the boom feet 22 are
symmetrical about the axis 30 of the post 5 on a plane that is
perpendicular to the axis 30 (i.e., the machine deck 50). Thus, if
FIG. 5 were an illustration of the full diameter of the post 5 and
the machine deck 50, in one embodiment, a back roller 95 would be
visible at the seven-thirty position and another boom foot 22 would
be visible at approximately the ten o'clock position. Also, one
would see that the roller chain bearing 100 runs continuously from
the three o'clock position, past the twelve o'clock position, to
the nine o'clock position. In other words, in one embodiment of the
invention, as shown in FIG. 5, the roller chain bearing 100
encompasses 180 degrees of the outer surface of the post 5. In
other embodiments, the roller chain bearing 100 encompasses greater
or lesser extents of the circumference of the outer surface of the
post 5. For example, in one embodiment, the roller chain bearing
100 encompasses 120 degrees of the outer surface of the post 5. In
another embodiment, the roller chain bearing 100 encompasses 270
degrees of the outer surface of the post 5. In yet another
embodiment, the roller chain bearing 100 encompasses the full 360
degrees of the outer surface of the post 5. In other embodiments,
the circumference segment of the post 5 encompassed by the roller
chain bearing 100 ranges from approximately 30 degrees to
approximately 360 degrees.
[0037] In one embodiment of the invention, as illustrated in FIG.
5, the last roller axle 120 at the end of the roller chain bearing
100 is anchored in an anchor bracket 155 that is secured to the
machine deck 50 and located at the three o'clock position. Again,
it should be noted that the arrangement of the roller chain bearing
100 and the back rollers is symmetrical about the axis 30 of the
post 5. Thus, if FIG. 5 were an illustration of the full diameter
of the post 5 and the machine deck 50, an anchor bracket 155 would
be visible at the nine o'clock position. In other embodiments of
the invention, the anchor brackets 155 are located at other
positions about the outer surface of the post 5. For example, in
one embodiment, the anchor brackets 155 anchoring the ends of the
roller chain bearing 100 are located at the seven-thirty and
four-thirty positions. In other embodiments, the anchor brackets
155 are located at other locations about the circumference of the
post 5.
[0038] In another embodiment, as shown in FIGS. 6 and 7, the anchor
bracket 155 is located at approximately the four o'clock position.
The anchor bracket 155 has a pair of extended link plates 160 that
run between the axle 120 of the last roller 105 of the roller chain
bearing 100 at the three o'clock position and the anchor bracket
155. The extended link plates 160 tangentially leave the
circumference of the post 5 at the three o'clock position as they
run to the anchor bracket 155. Again, because the anchor bracket
155 arrangement is symmetrical about the circumference of the post
5, a pair of extended link plates 160 run between the axle 120 of
the last roller 105 of the roller chain bearing 100 at the nine
o'clock position to an anchor plate 155 located at approximately
the eight o'clock position.
[0039] As illustrated in FIGS. 3 and 5, the roller axle 120 located
at the anchor bracket 155 is extended and resides in a hole 162 in
an anchor block 165. The hole 162 is off-center from the
geometrical center point of the anchor block 165. Pivoting the
anchor block results in a cam-action that allows the roller chain
bearing 100 to be adjusted in length about the outer circumference
of the post 5 for typical roller wear.
[0040] As shown in FIG. 5, the rollers 105 are evenly distributed
along the length of the roller chain bearing 100. For example, in
one embodiment, there is a ten-degree spacing between each roller
105 about the axis 30 of the post 5. In another embodiment, there
is a five-degree spacing between each roller 105 about the axis 30
of the post 5. In another embodiment, there is a 15-degree spacing
between each roller 105 about the axis 30 of the post 5. In other
embodiments, the range of possible equal spacings for the rollers
105 about the axis 30 of the post 5 will be from approximately two
degrees to approximately 20 degrees.
[0041] As illustrated in FIG. 3, in one embodiment of the
invention, the roller chain bearing 100 is supported above the
machine deck 50 and prevented from displacing vertically along the
outer circumference of the post 5 by pads 170 located below some or
all of the axles 120 of the roller chain bearing 100. In another
embodiment, structural members are secured to the machine deck 50
at various locations adjacent to the outer circumference of the
roller chain bearing 100. The structural members have flanges that
extend below the top fixed link plate 115, thereby supporting the
roller chain bearing 100 above the machine deck 50 and preventing
the vertical displacement of the roller chain bearing 100 along the
outer circumference of the post 5. In another embodiment, the
stiffness and mass of the roller chain bearing 100, along with the
thrust loads exerted on the roller chain bearing 100 by the boom
10, combine to prevent the vertical displacement of the roller
chain bearing 100 without additional structural support.
[0042] Another means of preventing vertical displacement of the
roller chain bearing 100 is illustrated in FIG. 8, which is a
lateral cross-section elevation view of the roller chain bearing
100, wherein the view cuts across the pivot link plates 110 between
two rollers 105. As shown in FIG. 8, the rollers 105 of the roller
chain bearing 100 have flanges 175 for mating with a rail 180
encircling the outer circumference of the post 5. In another
embodiment, the roller 105 has a double inclined face for mating
with a rail 180 having a V profile. In other embodiments, the
roller 105 and rail 180 will have a circle segment or other
cross-sectional profiles that will allow the bearing surface of the
roller 105 and rail 180 to mate, align and prevent vertical
displacement of the roller chain bearing 100 along the outer
circumference of the post 5.
[0043] As can be seen from FIG. 5, as the machine deck 50 of the
superstructure 20 rotates about the axis 30 of the post 5, the back
rollers 90, 95 and the rollers 105 of the roller chain bearing 100
roll along the outer surface of the circumference of the post 5 and
transfer any radial (i.e., horizontal) thrust load from the boom 10
to the post 5. The pivot link plates 110 of the roller chain
bearing 100 allow the roller chain bearing 100 to flex to conform
to the outer circumference of the post 5. In other words, in one
embodiment, the roller chain bearing 100 is a series of flexibly
linked rollers 105 that form a radial bearing surface that conforms
to at least a portion of a radial bearing surface on the outer
circumference of the post 5.
[0044] The roller chain bearing 100 is advantageous because it
provides an effective method of substantially equalizing roller
loads without having to rely on precision machining or elastic
deflections to equally share roller loads. When a slewing gear
assembly 85 that is removable in segments is used, the
configuration and location of the roller chain bearing 100 also
eases servicing. Specifically, the structure allows the replacement
or other servicing of the means of resisting radial (i.e.,
horizontal) thrust from the boom 10 without having to remove the
boom 10, the machine deck 50, or superstructure 20.
[0045] Although the present invention has been described with
reference to preferred embodiments, persons skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
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